This invention relates to body frame components for motor vehicles which have a specific shape and are designed to absorb a force acting on the component which, because of the specific shape of the body frame component, produces differing load or stress conditions within different regions of the component when the force is being applied, in particular, high load or stress conditions in a first region and low load or stress conditions in a second region.
The invention furthermore relates to a method of producing a motor vehicle, which is formed by reshaping an essentially flat material to produce a specific shape which can be fitted within a vehicle body and which, when fitted in the body, absorbs at least one force acting on the body frame component, and in which the specific shape of the body frame component results in differing load or stress conditions being produced within different regions of the body frame component when the force is being applied.
The prior art discloses body frame components which can be produced in a variety of ways so that the overall weight of a motor vehicle containing the components is as low as possible. In order for such body frame components to absorb forces acting on them, the components have a specific shape and a material thickness corresponding to their purpose. The material thickness differs in different regions of the component depending on the loads or stresses which may occur in those regions. Thus, in regions having high load or stress conditions, a far greater thickness of material is provided than in regions having low load or stress conditions.
Weight-saving body framework components have, until now, been produced with the aid of the "tailored-blank" technique. In this technique, various metal elements, generally metal sheets of differing structure which also have differing sheet thicknesses, are welded to one another in such a manner that a body frame component having a specific shape is produced. This body frame component has differing wall thicknesses or material thicknesses in different regions because of the use of metal sheets of differing sheet thickness. Furthermore, body frame components of this type having differing wall thicknesses provided in different regions may also be produced by die-casting, which is expensive.
German Offenlegungsschrift No. 25 58 332 and European Patent No. 0 633 182 disclose separate structural elements which are perforated sheets or steel lattices and are fastened to the inside of hoods or doors of a vehicle in order to increase mechanical strength or rigidity. Such structural elements are bonded onto the corresponding regions of a vehicle door or are connected to the vehicle-door panel by cold deformation.
The conventional body frame components which are produced with the aid of the "tailored-blank" methods or by die-casting are not of optimum design, on the one hand, and, on the other hand, the methods of producing them are very expensive. Experience has shown that the complex body frame components to be produced with the aid of the "tailored-blank" method can only be manufactured at high cost since various metal sheets of differing structure must be used and the appropriate manufacturing tolerances for the body frame component are difficult to maintain during assembly. Furthermore, the welds in the components not only have to be designed precisely but they also have to absorb the corresponding forces, and welds within the body frame component constitute weak points. As a result, the entire method for this type of production is extremely time-consuming.